Apparatus for treating exhaust gas in a processing system

ABSTRACT

Methods and apparatus for treating an exhaust gas in a foreline of a substrate processing system are provided herein. In some embodiments, a method for treating an exhaust gas in an exhaust conduit of a substrate processing system includes: flowing an exhaust gas from a process chamber into a plasma source via a foreline; injecting a reagent into the foreline; forming a plasma in the plasma source from the exhaust gas and the reagent; and injecting a cleaning gas into the foreline, wherein the cleaning gas and the reagent are different gases.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of co-pending U.S. patent applicationSer. No. 15/449,226, filed Mar. 3, 2017, which is a divisional of U.S.patent application Ser. No. 14/300,372, filed Jun. 10, 2014 and issuedas U.S. Pat. No. 9,597,634 on Mar. 21, 2017, which is a continuation ofU.S. patent application Ser. No. 12/957,539, filed Dec. 1, 2010 andissued as U.S. Pat. No. 8,747,762 on Jun. 10, 2014, which claims benefitof U.S. provisional patent application Ser. No. 61/266,396, filed Dec.3, 2009. Each of the aforementioned related patent applications isherein incorporated by reference in its entirety.

FIELD

Embodiments of the present invention generally relate to the manufactureof electronic devices, and more specifically, to systems and methods forabating exhaust from electronic device manufacturing systems.

BACKGROUND

Remote plasma sources (RPS) or in-line plasma sources (IPS) have beenused for abatement of perfluorocarbons (PFC's) and global warming gases(GWG's). For example, the RPS or IPS may be installed in a foreline of avacuum system of a substrate processing system between a high vacuumpump, such as a turbo pump, and a backing pump, such as a dry vacuumpump. However, there is currently no method or apparatus to control anoperating pressure of the foreline (and hence the RPS or IPS) tooptimize abatement of PFCs and/or GWGs. Accordingly, the inventors haveprovided improved methods and apparatus for treating exhaust gas in aprocessing system.

SUMMARY

Methods and apparatus for treating an exhaust gas in a foreline of asubstrate processing system are provided herein. In some embodiments,methods and apparatus may be provided to control foreline pressure tocontrol and improve abatement destruction efficiency. In someembodiments, methods and apparatus may be provided to supply anintermittent or continuous cleaning gas flow to remove deleteriousdeposits that can accumulate on surfaces of a plasma abatement devicecoupled to the foreline. In some embodiments, the cleaning gas flow maybe synchronized to the process for optimal cleaning and maximumsubstrate throughput.

In some embodiments, methods to selectively activate the pressurecontrol or clean in sequence with the tool process recipe are providedto enhance the efficiency, throughput, and uptime of the system. In someembodiments, methods for cost effectively providing accurate andrepeatable control of the reagent delivery rate are also provided. Thecombination of reagent injection control along with foreline pressurecontrol may be provided to manage the plasma within an optimal operatingrange (for PFC or global warming gas abatement) in real-time.

In some embodiments, an apparatus for cleaning a foreline of a substrateprocessing system may include a plasma source coupled to a processforeline of a process chamber; a reagent source coupled to the processforeline upstream of the plasma source; and a foreline gas injection kitcoupled to the process foreline to controllably deliver a gas to theprocess foreline, wherein the foreline injection kit includes: apressure regulator to set a foreline gas delivery pressure setpoint; agauge to monitor the foreline gas delivery pressure; and a fixed orificeto provide a known flow of gas at the pressure setpoint of the pressureregulator. In some embodiments, the foreline gas injection kit mayfurther include an on/off control valve to selectively turn on and offthe flow of the foreline gas to the process foreline. In someembodiments, the foreline gas injection kit may further include apressure transducer to provide a signal corresponding to the pressure ofthe foreline gas; and a controller coupled to the signal from thepressure transducer to provide a feedback loop to control the pressureof the foreline gas.

In some embodiments, an apparatus for treating an exhaust gas in aforeline of a substrate processing system includes a plasma sourcecoupled to a foreline of a process chamber, a reagent source coupled tothe foreline upstream of the plasma source, and a foreline gas injectionkit coupled to the foreline to controllably deliver a gas to theforeline, wherein the foreline injection kit includes a pressureregulator to set a foreline gas delivery pressure setpoint, and a firstpressure gauge coupled to monitor a delivery pressure of the gasupstream of the foreline.

In some embodiments, a method for treating an exhaust gas in a forelineof a substrate processing system including flowing an exhaust gas and areagent gas into a foreline of a substrate processing system, forming aplasma from the exhaust gas and reagent gas to convert the exhaust gasto abatable byproduct gases, and injecting a non-reactive gas into theforeline to maintain a desired pressure in the foreline for optimalconversion of the exhaust gas. Other and further embodiments of thepresent invention are described below.

Other and further embodiments of the present invention are describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention, briefly summarized above anddiscussed in greater detail below, can be understood by reference to theillustrative embodiments of the invention depicted in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this invention and are thereforenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments.

FIG. 1 depicts a substrate processing system in accordance with someembodiments of the present invention.

FIG. 2 depicts a substrate processing system in accordance with someembodiments of the present invention.

FIG. 3 depicts a substrate processing system in accordance with someembodiments of the present invention.

FIG. 4 depicts a flow chart of a method for treating an exhaust gas inaccordance with some embodiments of the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Methods and apparatus for treating an exhaust gas in a foreline of asubstrate processing system are provided herein. Embodiments of thepresent invention may advantageously provide improved abatementefficiency for perfluorocarbons (PFC's) and global warming gases(GWG's). Embodiments of the present invention may improve abatementefficiency by, for example, controlling a pressure in the foreline tooptimize breakdown of PFCs and/or GWGs by reaction with one or morereagent gases. For example, the pressure may be controlled in real-timeto maintain the pressure within a desired operating range, or may beadjusted in response to one or more reagent gases injected into theforeline.

For example, in some embodiments, a plasma including a reagent (such aswater) may be formed in or delivered to the process foreline whilecontrolling the pressure in the process foreline to more optimally formand/or maintain the plasma. In some embodiments, methods to selectivelyactivate the pressure control in sequence with the tool process recipeare provided to enhance the efficiency of the system. In someembodiments, methods for cost effectively providing accurate andrepeatable control of the reagent delivery rate are also provided. Thecombination of reagent injection control along with foreline pressurecontrol may be provided to manage the plasma within an optimal operatingrange (for PFC or GWG abatement) in real-time.

Embodiments of the present invention enable an in-line plasma abatementsystem (for example as schematically depicted in FIG. 1) to maintainoptimum abatement efficiency while minimizing use of foreline pressurecontrol gases (such as N₂ or other gases discussed below), plasmareagents (such as water or other reagents discussed below), andelectricity. The optimization can be optionally managed by real-timesensor feedback (examples include pressure, flow, and temperature),pre-determined operating conditions corresponding to each step in therecipe, or input from the process tool and gas control signals. Thecontrolled, post-plasma foreline gas injection enables local linepressure control to optimize abatement performance. Alternatively, theforeline gas could be added pre-plasma (e.g., upstream of the RPS orIPS). However, a pre-plasma foreline gas addition would requireconsiderably more plasma energy to fracture the foreline gas and thegases being abated (such as PFC's and GWG's) and could result inpressure cross-talk back to the process chamber.

Additional advantages of the post-plasma foreline gas injection includethe reduction in temperature of the post abatement exhaust. As thepressure and gas flow in the exhaust line can change with each step inthe recipe, this invention can adjust to each change in the recipe orfor each operational condition to maintain optimum abatement efficiencywhile minimizing utilities and energy use for step. This control can beby set parameters time-synchronized to the process recipe, by real-timesensor feedback, or by monitoring the tool or gas panel control signals.If the abatement tool is in shutdown, idle, preventative maintenance, orbypass mode, energy and utilities can be minimized by use of the smartinterface between the process chamber and the abatement device. Forexample, the smart interface may adjust the plasma power supply outputto an appropriate power level to maintain target performance. The plasmapower supply and reactor tube (or other component) lifetime depend onoperating energy level. Wasting power by operating at a plasma energylevel higher than is required for the abatement or clean gas within thereactor not only wastes energy, but shortens the duration betweenrequired maintenance. Further the abatement RPS or Inline AbatementDevice smart interface may count and report: uptime, system warnings orfaults, operating efficiency, operational hours, and utilities used, andmay report real time or accumulative carbon footprint performancelocally or to a central monitoring and reporting system. Furtherembodiments of this invention include a reagent delivery system designedand integrated with the foreline gas injection control to maintain adesired amount of reagent injected to the exhaust pre-plasma to maintainoptimum abatement efficiency of PFC or GWG and to minimize reagentconsumption.

A plasma source for foreline abatement may utilize a hydrogen or oxygencontaining reagent, such as water vapor, in addition to the processexhaust, to enable PFC and GWG abatement in the foreline. FIG. 1 is apiping and instrumentation diagram that shows a typical plasma forelineabatement system in accordance with some embodiments of the invention.The plasma foreline abatement system may be coupled to or may be part ofa larger processing system that produces or emits PFC's or GWG's thatrequire abatement. Non-limiting examples of such systems includesubstrate processing systems such as those used in semiconductor,display, solar, or light emitting diode (LED) manufacturing processes.

For example, FIG. 1 depicts a schematic diagram of a substrateprocessing system 100 in accordance with some embodiments of the presentinvention. As shown in FIG. 1, an exhaust conduit, or foreline 102 (forexample, coupled to a process chamber or tool to carry exhaust from thechamber or tool, as indicated at 101), may be provided with a plasmasource 104 (such as a remote plasma source (RPS)) coupled in-line withthe foreline 102. The plasma source 104 may be implemented as a radicalinjector (e.g., an RPS) or as a process flow-through device (e.g., anIPS, where a plasma is created in the conduit through which the processexhaust flows). The plasma source 104 may be any plasma source coupledto the foreline 102 suitable for developing a plasma therein (such as aremote plasma source, an in-line plasma source, or the other suitableplasma source for generating a plasma—such as a capacitively coupled,inductively coupled, remote, or standing wave plasma—within the forelineor proximate the foreline and introduced into the foreline). Theembodiments of FIGS. 1-3 are schematically represented and somecomponents have been omitted for simplicity. For example, a high speedvacuum pump, such as a turbo pump or the like, may be disposed betweenthe process chamber 101 and the foreline 102 for removing exhaust gasesfrom the process chamber 101.

A reagent delivery system 106 may be coupled to the foreline 102 todeliver a reagent, such as water vapor, to the foreline 102 upstream ofthe plasma source 104. The reagent delivery system 106 may include areagent source 105 (or multiple reagent sources (not shown)) coupled tothe foreline 102 via one or more valves. For example, in someembodiments, a valve scheme may include a control valve 103 which actsas an on/off switch for releasing reagent from the reagent source 105and a flow control device 107 for controlling the flow rate of reagentinto the foreline 102. For example, as shown in FIG. 1, the flow controldevice 107 can be disposed between the foreline 102 and the controlvalve 103. The control valve 103 may be any suitable control valve suchas a solenoid valve or the like. The flow control device 107 may be anysuitable active or passive flow control device, for example, such as afixed orifice, mass flow controller, needle valve or the like. In someembodiments, the reagent delivery system 106 may provide water vapor. Insome embodiments, the reagent delivery system 106 may provide oxygen(O₂). However, use of O₂ as a reagent introduced into the foreline 102may result in the formation of OF₂, which is very toxic. As such, O₂ maybe used as a reagent primarily in regions where local regulations allowand/or where appropriate safety accommodations are in place.

Alternatively or in combination, reagents or additional reagents may beprovided to the foreline 102 via a source coupled to the process chamber101, such as from a gas panel or the like. For example, in someembodiments, a gas panel and control system 111 coupled to the processchamber 101 can be used to supply a flow of a cleaning gas to theforeline 102 upstream of the plasma source 104. The cleaning gas mayfacilitate removing deleterious deposits that can accumulate on surfacesof the plasma source 104, such as a lumen of a reactor tube of theplasma source 104.

The flow of the cleaning gas may be intermittent or continuous. The flowof the cleaning gas may be synchronized to the process for optimalcleaning and maximum substrate throughput. The cleaning gas may be mosteconomically provided by the existing process gas panel and controlsystem, which can supply any cleaning gas (such as, NF₃, O₂, Ar, COF₂,H₂O, F₂ or the like) either through the chamber (as shown) or optionallythrough a chamber bypass line (as shown by dashed line 113) thatprovides the cleaning gas prior to, or upstream of, the plasma source104. In addition to providing optimal species to the plasma source 104for cleaning, the intermittent or continuous addition of clean gas maybe used to facilitate managing line pressure to provide optimal cleaningof deposits from the plasma abatement reactor tube. Although depictedonly in FIG. 1, the gas panel and control system 111 and the methods ofuse thereof may be incorporated in any of the embodiments disclosedherein.

A foreline gas injection kit 108 may be coupled to the foreline 102upstream or downstream of the plasma source 104 (downstream depicted inFIG. 1) to controllably provide a foreline gas, such as nitrogen (N₂),argon (Ar), or clean dry air (CDA), into the foreline 102 as desired tocontrol the pressure within the foreline 102. In some embodiments, theforeline gas being added may also control the exhaust gas temperaturedownstream of the device. Reducing the temperature of the foreline maysignificantly reduce failure of the foreline and other post abatementelastomeric or metal seals, and process pump components.

In some embodiments, such as shown in FIG. 1, the foreline gas injectionkit 108 may include a foreline gas source 109 followed by a pressureregulator 110 to set the gas delivery pressure setpoint, furtherfollowed by a control valve 112 to turn on and off the flow and finallya flow control device 114 such that a known flow of gas may be providedat the specific setpoint of the pressure regulator 110. The controlvalve 112 may be any suitable control valve, such as discussed above forcontrol valve 103. The flow control device 114 may be any suitable flowcontrol device, such as discussed above for flow control device 107. Insome embodiments, the flow control device 114 is a fixed orifice. Insome embodiments the foreline gas injection kit 108 may further includea pressure gauge 116, for example, disposed between the pressureregulator 110 and the flow control device 114. For example, the pressuregauge 116 may be used to measure pressure in the kit 108 upstream of theflow control device 114. For example, the measured pressure at thepressure gauge 116 may be utilized by a control device, such as acontroller 118 discussed below, to set the pressure upstream of the flowcontrol device 114 by controlling the pressure regulator 110.

In some embodiments, the control valve 112 may be controlled by thesystem (e.g., controller 118) to only turn gas on when the reagent fromthe reagent delivery system is flowing, such that usage of gas isminimized. For example, as illustrated by the dotted line betweencontrol valve 103 of the reagent delivery system 106 and the controlvalve 112 of the kit 108, the control valve 112 may turn on (or off) inresponse to the control valve 103 being turned on (or off). In someembodiments, the reagent may flow only when the plasma abatement unit isturned on and commanded to abate the process. Alternative methods ofcontrol can be used other than the embodiment described above, such as amass flow controller or a flow control needle valve instead of the fixedsize orifice. In some embodiments a time delay or pre-activation of linepressure or reagent addition control may be employed for optimalperformance results and plasma stability.

The foreline 102 may be coupled to a vacuum pump or other suitablepumping apparatus, as indicated at 120, to pump the exhaust from theprocessing tool to appropriate downstream exhaust handling equipment(such as abatement equipment or the like). In some embodiments, thevacuum pump 120 may be a backing pump, such as a dry mechanical pump orthe like. For example, the vacuum pump 120 may have a variable pumpingcapacity with can be set at a desired level, for example, to control orprovided addition control of pressure in the foreline 102.

The controller 118 may be coupled to the foreline abatement system forcontrolling the operation thereof. The controller 118 may be providedand coupled to various components of the substrate processing system 100to control the operation thereof. For example, the controller maymonitor and/or control the foreline gas injection kit 108, the reagentdelivery system 106, and/or the plasma source 104 in accordance with theteachings disclosed herein. In some embodiments, the controller may bepart of or coupled to a controller (not shown) of the process chamber101 coupled to the foreline 102 to control the foreline abatement systemin concert with the processing and recipes running in the processchamber.

The controller 118 may include a central processing unit (CPU), amemory, and support circuits. The controller 118 may control thesubstrate processing system 100 directly, or via computers (orcontrollers) associated with particular process chamber and/or supportsystem components. The controller 118 may be one of any form ofgeneral-purpose computer processor that can be used in an industrialsetting for controlling various chambers and sub-processors. The memory,or computer readable medium, of the controller 118 may be one or more ofreadily available memory such as random access memory (RAM), read onlymemory (ROM), floppy disk, hard disk, optical storage media (e.g.,compact disc or digital video disc), flash drive, or any other form ofdigital storage, local or remote. The support circuits are coupled tothe CPU for supporting the processor in a conventional manner. Thesecircuits include cache, power supplies, clock circuits, input/outputcircuitry and subsystems, and the like. Inventive methods as describedherein may be stored in the memory as software routine that may beexecuted or invoked to control the operation of the substrate processingsystem 100 in the manner described herein. The software routine may alsobe stored and/or executed by a second CPU (not shown) that is remotelylocated from the hardware being controlled by the CPU of the controller118.

The configuration in FIG. 1 is exemplary and other variants ofcomponents may be provided to supply the foreline gas, the reagent,and/or the plasma. In addition, other components may be included in thesubstrate processing system 100 to provide enhanced functionality,efficiency, ease of use, or the like. For example, in some embodiments,and as shown in FIG. 2, a vacuum valve 122 and a port 124, such as an N₂blanked port, may be coupled to the foreline 102 for temporaryconnection of a vacuum gauge for preliminary setup, testing, and thelike. In some embodiments, the vacuum valve 122 and the port 124 may becoupled to the foreline 102 between the plasma source 104 and theforeline gas injection kit 108.

In some embodiments, as shown in FIG. 3, a pressure gauge 126, such as avacuum pressure transducer or the like, may be provided in the foreline102 provide a pressure signal that may be used, for example, by thecontroller 118 in a feedback loop to control the regulating pressure ofa pressure control valve 110 or the flow rate of the flow control device114, for example in embodiments where a mass flow controller is used, toenable dynamic control of the operating pressure of the plasma source104, e.g., the pressure in the foreline 102. In some embodiments, forexample when the vacuum pump 120 has variable pumping capacity, thecontroller may adjust the pumping capacity of the vacuum pump 120 inresponse to a foreline pressure measured by the pressure gauge 126.

FIG. 4 depicts a flow chart for a method 400 for treating an exhaust gasin the foreline of a processing system. For example, the method 400 maybe utilized with any of the embodiments of the substrate processingsystem 100 discussed herein. The exhaust gas may include a variety ofexhaust gases resultant from performing a process in the process chamber101, such as unreacted process gases, byproduct gases formed from theinteraction of one or more process gases and/or interaction of a processgas with a substrate, or the like. Exhaust gases that may benefit fromthe methods disclosed herein include, but are not limited to, PFCs andGWGs. The method 400 begins at 402 by flowing an exhaust gas and areagent gas into a foreline, such as the foreline 102, of a substrateprocessing system, such as the substrate processing system 100. Forexample, the exhaust gas may have originated at the process chamber 101and resulted from performing any of a number of processes, such asetching, deposition, cleaning, or the like. The reagent gas may beinjected into the foreline 102, for example, by the reagent deliverysystem 106.

At 404, a plasma may be formed form the exhaust gas and the reagent gasto convert the exhaust gas in abatable byproduct gases. For example, theabatement process can be illustrated by the following simple chemicalformulas, for example, for CF₄ or NF₃ breakdown via plasma:CF₄+2H₂O=CO₂+4HFCF₄+H₂O=COF₂+2HF4NF₃+6H₂O=2N₂+12HF+3O₂

The PFC or other global warming gas (CF₄ and NF₃ in the exemplaryembodiments above), is reacted to break down the global warming gas andconvert the fluorine to HF, which is easily scrubbed by traditional wetscrubbing technologies.

The ability of a remote plasma source or in-line plasma source todeliver energy to the plasma is dependent on matching of the powercircuit of the remote plasma source to the operating process conditions.Hence, if the pressure in the vacuum foreline is too low, as a result oflow process flow or large safety factor incorporated in the design ofthe vacuum system, it is not possible to deliver full power to theplasma and consequently the destruction efficiency for the PFC and GWGis undesirably reduced.

Accordingly, and at 406, a non-reactive gas may be injected into theforeline 102 to maintain a desired pressure in the foreline for optimalconversion of the exhaust gas. For example, the non-reactive gas may beinjected by the foreline gas injection kit 108. In some embodiments, forexample as illustrated in FIG. 1, a first amount of the non-reactive gasmay be injected in response to a second amount of the reagent gas flowedinto the foreline 102. For example, the controller may control thecontrol valve 112 of the kit 108 to open or close in response to theopening or closing of the control valve 103 of the reagent deliverysystem 106. Alternatively, the injection of the non-reactive gas may beresponse to a pressure level in the foreline 102. For example, thepressure level in the foreline 102 as indicated by the pressure gauge126 may be monitored by the controller 118. The controller may adjustthe flow rate of the non-reactive gas in the foreline 102 in response tothe monitored pressure level. For example, the controller 118 may adjustone or more of the pressure regulator 110 or the flow control device 114to maintain the desired pressure level in the foreline 102.

In some embodiments, the method 400 may include flowing a cleaning gasinto the foreline 102 to remove material deposited during conversion ofthe exhaust gas. For example, material may accumulate on one or more ofsurfaces of the foreline 102 or surfaces of the plasma source 104. Theflowing of the cleaning gas may occur, for example, between a desirednumber of process runs performed in the substrate processing system 100.For example, a desired number of process runs may include between eachsubstrate being processed, between a desired number of substrates beingprocessed, or the like. Further, the cleaning gas may be provide by anyof a number of sources, for example from the reagent delivery system106, or from the process chamber 101, such as via a gas panel or thelike.

In some embodiments, in operation, the foreline pressure and thestoichiometric ratio of water to a target species being abated with theplasma may be controlled, both separately and in concert with eachother, for plasma abatement optimization. Embodiments of the presentinvention allow for tuning and setting fixed setpoints for theseparameters. In some embodiments, the circuits may be tuned to controlwater ratio and local pressure via a pre defined recipe. In someembodiments, signals from the process controller may be used to setconditions, or signals from the chamber or process controller to the gasbox may be used to control these setpoints. In some embodiments, inaddition to controlling the foreline pressure and the stoichiometricratio of water to a target species being abated with the plasma, theplasma power and RF match characteristics may also be tuned fordifferent steps/parts of the process recipe. In addition to real time,by feedback sensor(s), or by recipe control of foreline pressure andcontrol of stoichiometric ratio of water, in some embodiments the poweroutput from the power supply may also be varied to add more power to theplasma for process steps that require greater power to achieve desireddestruction removal efficiency and reduce the power consumption forsteps that do not require as much power to achieve desired DRE.

For example, test results of processing in accordance with embodimentsof the present invention show that the addition of a foreline gasinjection kit to the system advantageously allows the pressure in theremote plasma source to be controlled for optimum power delivery to theplasma. Some embodiments of the invention may use a pressure regulatorto set the nitrogen delivery pressure to a known setpoint, followed by acontrol valve to turn on and off the flow and finally an appropriatelysized orifice such that a known flow of gas is provided at the specificset point of the pressure regulator. The nitrogen On/Off control valvemay be controlled by the system to only turn gas on when water vapor isflowing such that usage of nitrogen is minimized. In some embodiments,the water vapor flow may flow only when the remote plasma abatement unitis turned on and commanded to abate the process. Alternative methods ofnitrogen control can be used other than the embodiment described above,such as a mass flow controller or a flow control needle valve instead ofthe fixed size orifice. In some cases, for optimal operating conditions,a delayed or preemptive control signal may be used to start or stopreagent or foreline pressure flow control.

High abatement efficiency is also dependent on accurate setting of thewater flow rate. The water delivery system includes a water tank thatoperates under vacuum conditions such that the water boils at lowtemperature from ambient to about 35 degrees Celsius. Control of thewater vapor flow rate may be determined by the adjustment of the flowcontrol device 107. To enable accurate setting of this valve andrepeatability of the setting, a micrometer needle valve has beenincorporated so that the set point can be dialed in and specifiedprecisely for a specific recipe, tool set, and/or operating condition.Once an application set point has been defined, future unitsmanufactured for the application can be factory preset to the desiredsetting.

Although discussed above in context of an exhaust line abatement system,embodiments of the present invention may also apply to abatement, linecleaning, and chamber clean plasma applications.

Thus, methods and apparatus for treating an exhaust gas in a foreline ofa substrate processing system have been provided herein. Embodiments ofthe present invention may advantageously provide improved abatementefficiency for perfluorocarbons (PFC's) and global warming gases(GWG's). Embodiments of the present invention may improve abatementefficiency by controlling a pressure in the foreline to optimizebreakdown of PFCs and/or GWGs by reaction with one or more reagentgases. For example, the pressure may be controlled in real-time tomaintain the pressure within a desired operating range, or may beadjusted in response to one or more reagent gases injected into theforeline.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

What is claimed is:
 1. A non-transitory computer readable medium havinginstructions stored thereon that, when executed, cause a method to beperformed, the method comprising: injecting a reagent into a foreline,the foreline configured to remove exhaust gas from a process chamber;forming a plasma in a plasma source from the exhaust gas and thereagent; and injecting a cleaning gas into the foreline, wherein thecleaning gas and the reagent are different gases.
 2. The computerreadable medium of claim 1, wherein the reagent and the cleaning gas areinjected into foreline upstream of the plasma source.
 3. The computerreadable medium of claim 1, wherein the cleaning gas is injected intothe plasma source intermittently.
 4. The computer readable medium ofclaim 1, wherein the cleaning gas is injected into the plasma sourcecontinuously.
 5. The computer readable medium of claim 1, wherein thereagent comprises water and the cleaning gas comprises oxygen gas.
 6. Asystem, comprising: a process chamber; a foreline to flow an exhaust gasfrom the process chamber; a plasma source coupled in-line with theforeline; a reagent delivery system to inject a reagent into theforeline; a gas panel to supply a flow of a cleaning gas to theforeline; and a controller configured to: inject the reagent into theforeline; form a plasma in the plasma source from the exhaust gas andthe reagent; and inject the cleaning gas into the foreline, wherein thecleaning gas and the reagent are different gases.
 7. The system of claim6, wherein the reagent and the cleaning gas are injected into theforeline upstream of the plasma source.
 8. The system of claim 6,wherein the cleaning gas is injected into the plasma sourceintermittently.
 9. The system of claim 6, wherein the cleaning gas isinjected into t plasma source continuously.
 10. The system of claim 6,wherein the reagent comprises water and the cleaning gas comprisesoxygen gas.